Watertown, Massachusetts
Watertown Water Quality
MWRA reservoir water through Watertown's own mains. The 2025 lead result was 1.6 ppb at the 90th percentile — but the DPW letter also counts about 400 lead goosenecks among the Town's 7,600 services.
Lead 1.6 ppb at the 90th percentile · 0 of 20 over · ~400 lead goosenecks of 7,600 services.
The short answer
Watertown drinks MWRA water from the Quabbin and Wachusett Reservoirs, disinfected with chloramine. Its 2025 lead result was 1.6 ppb at the 90th percentile — well under the 15 ppb action level — with none of 20 samples over.
The Watertown-specific detail is the gooseneck: the DPW letter says about 400 of 7,600 services had a lead gooseneck at the start of 2025, even though the inventory calls almost all service lines non-lead. Ask the DPW what its records show for your address, then test at the tap.
Get a free test
Tell us your Watertown address. We confirm coverage first, then schedule a licensed technician to test at your tap — no charge, no obligation.
What filtration does — and does not
Softening, carbon and reverse osmosis solve different problems. A filter is not a substitute for replacing a lead gooseneck or service line.
Where Watertown water comes from
The same reservoirs as Boston, through Watertown's own pipes.
Quabbin and Wachusett Reservoirs
Watertown purchases its water from the MWRA, whose sources are the Quabbin and Wachusett Reservoirs in central and western Massachusetts.
Treated by MWRA before it arrives
MWRA treats the water at the John J. Carroll Water Treatment Plant in Marlborough, adjusting pH and alkalinity to reduce corrosion and disinfecting with monochloramine (2025 average 1.99 ppm).
Then Watertown's own mains
The Town's DPW delivers it through about 82 miles of water main, 2 to 16 inches, to roughly 7,600 service connections.
What the 2025 Watertown report actually says
Limits are fixed. Results are from MWRA's 2025 Drinking Water Test Results for Watertown, including the Town DPW letter — system-level figures, not a reading at your tap. A later report supersedes them.
Lead — 1.6 ppb at the 90th percentile
Watertown's 2025 round: 1.60 ppb at the 90th percentile against the 15 ppb action level, with a range of non-detect to 3.53 ppb and no sample over the action level.
About 400 lead goosenecks
The DPW letter says that at the start of 2025 approximately 400 of the 7,600 services in the system had lead goosenecks — short flexible connectors where a service line changes direction or meets the main.
Copper — 70.1 ppb
90th percentile (range 14.3–84.9 ppb) against a 1,300 ppb action level. No sample exceeded it.
Inventory: “almost all” non-lead
Watertown finished its first service-line inventory in October 2024 and submitted it to MassDEP. At the end of 2025 it mailed letters to each property its records show with a lead service line that could contribute lead.
Two schools tested in 2025
The Hosmer School and the JR Lowell Elementary School were tested for lead and copper in 2025; results were below action levels.
Coliform — in compliance
Watertown collects more than 500 samples a year for total coliform at the MWRA lab and reports compliance with all applicable drinking water standards for 2025.
Watertown next to Waltham, Cambridge and Brookline
Upstream on the Charles, Waltham also buys MWRA water; its 2024 inventory found no lead service lines but does not cover goosenecks. Cambridge is not an MWRA community at all and treats its own reservoir water at Fresh Pond. Brookline reported no identified lead service lines at the end of 2025. Across all MWRA communities, the Sept/Oct 2025 system result was 5.96 ppb with 18 of 594 samples over the action level — Watertown's 1.6 ppb sits well below that.
Where these figures come from
Everything on this page traces to MWRA and the Town of Watertown Department of Public Works.
- MWRA — 2025 Drinking Water Test Results, with the Town of Watertown DPW letter (PDF) — MWRA sources, treatment and system-wide results; Watertown's lead and copper results, gooseneck count, inventory status, coliform compliance and 2025 main and service work.
Matching treatment to the finding
Watertown's report supports checking for a gooseneck and a chloramine-aware filter choice — not a default equipment sale.
Ask the DPW about a gooseneck, not just the pipe
A service can be copper end to end and still have a lead gooseneck at the main or where it turns into the house. Watertown's DPW (617-972-6420) can tell you what its records show and how replacement works.
Test at the tap, first draw
The Town-wide 90th percentile is low. A tap test tells you whether your house — gooseneck, brass fixtures, older solder — matches it.
Certified lead filter as a stopgap
Where a lead gooseneck or lead-bearing plumbing is still in place, a filter certified to reduce lead at the kitchen tap is the practical stopgap until the part is replaced.
Chloramine taste: catalytic carbon or RO
MWRA disinfects with monochloramine. Ordinary carbon handles free chlorine better than chloramine; if taste or odour is the complaint, catalytic carbon or reverse osmosis is the right tool.
How the free test works
A licensed technician tests at your kitchen tap, walks the plumbing, and tells you which of the findings above applies to your house and which does not. There is no charge and no obligation.
Seamless Home is the licensed contractor of record on the work that follows. Installation is performed by vetted installing partners engaged as our subcontractors, and the workmanship obligation stays with us. Coverage is confirmed per service area rather than promised as blanket availability.
What a water treatment job with us covers
Installation and replacement of whole-home and point-of-use treatment, specified against what your water actually contains.
Sediment filtration
Installation of the first stage that protects everything downstream of it, sized to the service line and the household draw.
Softening
Installation of ion-exchange softening where hardness is the problem, including the drain connection the plumbing code treats as indirect waste.
Carbon filtration
Installation of carbon stages for taste, odour and disinfection by-products, specified from your utility's own water quality report.
Reverse osmosis
Point-of-use installation at the kitchen sink where the target is dissolved solids rather than whole-home flow.
Disinfection
Installation of UV or equivalent treatment where the supply is a private well or is otherwise not continuously disinfected.
System replacement
Replacing equipment that has reached the end of its service life, including the discharge and air gap details an inspector looks at.
This is installation and replacement work, specified from a published water quality report or a test of your supply — not from a sales chart. Coverage is confirmed per service area rather than promised as blanket availability.
What the work actually looks like
Treatment equipment is plumbing. Most of the job is the connection, the drain and the code detail behind it.
Watertown water, answered plainly
Where does Watertown's water come from?+
From the MWRA. Watertown buys treated water drawn from the Quabbin and Wachusett Reservoirs and delivers it through about 82 miles of Town main.
Did Watertown exceed the lead action level?+
No. The DPW letter in MWRA's 2025 report shows 1.60 ppb at the 90th percentile, a range of non-detect to 3.53 ppb, and none of 20 samples over the 15 ppb action level.
What is a lead gooseneck?+
A short, flexible piece of pipe used where a service line changes direction or connects to the main. Watertown's letter says about 400 of its 7,600 services had one at the start of 2025, even though the inventory describes almost all service lines as non-lead.
Does Watertown use chlorine or chloramine?+
Chloramine. MWRA disinfects with monochloramine before the water reaches Watertown; MWRA's 2025 average was 1.99 ppm.
Is Watertown water hard?+
This page doesn't quote a hardness figure because neither the Watertown letter nor the MWRA pages of the 2025 report give one. A tap test measures yours instead of guessing.
Where do these figures come from?+
MWRA's 2025 Drinking Water Test Results for Watertown, which includes the Town of Watertown DPW letter (PWS 3314000). Third-party aggregators are not used. A later report supersedes these figures.
Related resources
Home water purification and treatment
The national service page behind this one.
Learn more →Waltham water quality
Next door on MWRA water; a 2024 inventory with no lead service lines.
Learn more →Brookline water quality
MWRA water with no identified lead service lines at the end of 2025.
Learn more →Cambridge water quality
Not MWRA: its own reservoirs, treated at Fresh Pond.
Learn more →Boston water quality
The regional MWRA hub with the same reservoir water.
Learn more →All home services
Water, battery, HVAC and solar under one licensed contractor of record.
Learn more →Get a free test at your tap
A licensed technician tests at your kitchen tap and tells you which findings apply to your house — lead from a gooseneck or older plumbing, chloramine taste or none of them. No charge, no obligation, and coverage confirmed at your address first.
Get a free test